From: Jason Gunthorpe <jgg@nvidia.com>
To: Peter Xu <peterx@redhat.com>
Cc: "Kasireddy, Vivek" <vivek.kasireddy@intel.com>,
David Hildenbrand <david@redhat.com>,
"dri-devel@lists.freedesktop.org"
<dri-devel@lists.freedesktop.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
Mike Kravetz <mike.kravetz@oracle.com>,
Gerd Hoffmann <kraxel@redhat.com>,
"Kim, Dongwon" <dongwon.kim@intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
James Houghton <jthoughton@google.com>,
Jerome Marchand <jmarchan@redhat.com>,
"Chang, Junxiao" <junxiao.chang@intel.com>,
"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
"Hocko, Michal" <mhocko@suse.com>,
Muchun Song <muchun.song@linux.dev>,
John Hubbard <jhubbard@nvidia.com>
Subject: Re: [PATCH v1 0/2] udmabuf: Add back support for mapping hugetlb pages
Date: Fri, 23 Jun 2023 13:37:58 -0300 [thread overview]
Message-ID: <ZJXKZkxDKYxaJI/1@nvidia.com> (raw)
In-Reply-To: <ZJXJ4ULRKVN5JPyv@x1n>
On Fri, Jun 23, 2023 at 12:35:45PM -0400, Peter Xu wrote:
> It seems the previous concern on using gup was majorly fork(), if this is it:
>
> https://patchwork.freedesktop.org/patch/210992/?series=39879&rev=2#comment_414213
Fork and GUP have been fixed since that comment anyhow there is no
longer a problem using GUP and fork together.
> Could it also be guarded by just making sure the pages are MAP_SHARED when
> creating the udmabuf, if fork() is a requirement of the feature?
Also a resaonable thing to do
> For instance, what if the userapp just punchs a hole in the shmem/hugetlbfs
> file after creating the udmabuf (I see that F_SEAL_SHRINK is required, but
> at least not F_SEAL_WRITE with current impl), and fault a new page into the
> page cache?
It becomes incoherent just like all other GUP users if userspace
explicitly manipulates the VMAs. It is no different to what happens
with VFIO, qemu should treat this memory the same as it does for VFIO
memory.
Jason
next prev parent reply other threads:[~2023-06-23 16:38 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-22 7:27 [PATCH v1 0/2] udmabuf: Add back support for mapping hugetlb pages Vivek Kasireddy
2023-06-22 7:27 ` [PATCH v1 1/2] udmabuf: Use vmf_insert_pfn and VM_PFNMAP for handling mmap Vivek Kasireddy
2023-06-22 7:27 ` [PATCH v1 2/2] udmabuf: Add back support for mapping hugetlb pages Vivek Kasireddy
2023-06-22 22:10 ` kernel test robot
2023-06-22 8:25 ` [PATCH v1 0/2] " David Hildenbrand
2023-06-22 21:33 ` Mike Kravetz
2023-06-23 6:13 ` Kasireddy, Vivek
2023-06-23 16:35 ` Peter Xu
2023-06-23 16:37 ` Jason Gunthorpe [this message]
2023-06-23 17:28 ` Peter Xu
2023-06-26 12:57 ` Jason Gunthorpe
2023-06-26 7:45 ` Kasireddy, Vivek
2023-06-26 17:52 ` Peter Xu
2023-06-26 18:14 ` David Hildenbrand
2023-06-26 18:18 ` Jason Gunthorpe
2023-06-26 19:04 ` Peter Xu
2023-06-27 15:52 ` Jason Gunthorpe
2023-06-27 16:00 ` Peter Xu
2023-06-27 16:04 ` Jason Gunthorpe
2023-06-27 6:37 ` Kasireddy, Vivek
2023-06-27 7:10 ` David Hildenbrand
2023-06-28 8:04 ` Kasireddy, Vivek
2023-08-08 16:17 ` Daniel Vetter
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=ZJXKZkxDKYxaJI/1@nvidia.com \
--to=jgg@nvidia.com \
--cc=akpm@linux-foundation.org \
--cc=david@redhat.com \
--cc=dongwon.kim@intel.com \
--cc=dri-devel@lists.freedesktop.org \
--cc=jhubbard@nvidia.com \
--cc=jmarchan@redhat.com \
--cc=jthoughton@google.com \
--cc=junxiao.chang@intel.com \
--cc=kirill.shutemov@linux.intel.com \
--cc=kraxel@redhat.com \
--cc=linux-mm@kvack.org \
--cc=mhocko@suse.com \
--cc=mike.kravetz@oracle.com \
--cc=muchun.song@linux.dev \
--cc=peterx@redhat.com \
--cc=vivek.kasireddy@intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).